1. Field
The following description is related to a communication apparatus using Golay sequences and a data transmission/reception method thereof.
2. Description of Related Art
In an Orthogonal Frequency Division Multiplexing (OFDM) communication system, because a data stream is truncated to a plurality of sub data streams and the sub data streams are transmitted in parallel through sub-carriers, frequency selective fading and narrow-band interference can be alleviated. Thus, a large amount of data may be transmitted through sub-carriers.
Because an OFDM communication system has excellent performance in multipath and mobile communication environments, it has been used in wireless local area networks (WLANs), in wireless communication systems for digital broadcasts, and the like.
However, the OFDM communication system has several disadvantages. For example, a peak to average power ratio (PAPR) or peak-to-mean envelope power ratio (PMEPR) may be relatively high due to successive combinations of sub channels. The PAPR corresponds to a ratio of peak to average power ratio of multicarriers, and signals having a high PAPR deteriorate the power efficiency of an amplifier and hinder the orthogonality of data modulated by the sub carriers, resulting in reduced transmission efficiency.
Representative methods for reducing the PAPR include a method for clipping a part of a signal where the peak power appears through a filter, a method of multiplying codewords by weights for lowering the peak value for each region, and the like.
However, in the example of the clipping method, because some parts of signals are truncated, the signals may be distorted or out-of-band frequency characteristics may deteriorate. Also, in the example of the method of multiplying the codewords by the weights, because the weights have to be calculated for each region, additional pre-processing is needed and also there is inefficiency of having to transmit the calculated weights to a receiver.
Furthermore, because codewords are random, the above-described methods have a disadvantage in that PAPR reduction is not sufficient although the generation possibility of data distortion is reduced statistically.